Its interesting how Clara is the first to speak and say thats not possible. So are we to infer that now she now everything about the doctor due to her trip in the Doctors time stream. Kinda reminds me of the DoctorDonna and that she would know and be familiar with what the Doctor knows.

Knowing Moffat, I won't be surprised if the scarf is one of many bits of Doctor-associated paraphernalia that have been seeded throughout the timeline Bad Wolf-style by some wibbly-wobbly phenomenon, perhaps the latest universe-ending, reality-unravelling cataclysm that happens to revolve entirely around the Doctor because he's the most important being in the universe. The teaser trailer with all the familiar people and things from the series' history intermixed with each other may be more than just a tribute to the past but a hint of the actual storyline of the special.

Hmm, not the best trailer ever (a little too focused on explosions over any sense of real magic or wonder, and almost feels more like a typical season finale trailer), but the footage itself looks really good.

And is it just me, or is it surprisingly weird to hear Tennant as the Doctor again?